Since it's all about memory loss, the Brow Chakra or "third eye" (also good for seeing clearly) or the Crown Chakra would probably be best. For obvious reasons, Clark couldn't carry any stones around on his Chakras all day long.
Hmm... that's an interesting idea. He could wear a headband with the stone embedded in it. He might look like a goof, but if it helps and Star might just be out there enough to suggest it
Michael
